Hydraulic press technology for critical part manufacturing

While making aerospace parts via hydraulic-press technology may not come readily to mind for some manufacturers, many are successfully forming and fabricating critical metal and plastic/composite components with their presses. Today’s hydraulic presses offer manufacturers a number of benefits, including faster performance and increased reliability. Hydraulic press technology has seen significant improvements in seals, pumps, hoses, and couplings that have virtually eliminated leaks and minimized press maintenance.

Hydraulic presses can offer manufacturers considerable benefits, including time savings during setup and changeovers, flexibility for a wide range of applications, much lower operating costs, greater control, and space savings. Assessing current applications and press processes to determine if hydraulic-press technology can improve productivity is well worth the time and effort. It is an especially effective solution for the ever growing demands of smaller lots and varied applications – a trend that will only increase in the future. The following are some successful examples of how manufacturers are applying hydraulic press technology to make aerospace parts.
 

Pressing for composites

New composite parts are helping aerospace manufacturers reduce weight and increase fuel efficiency. A compression molding press proved to be an excellent choice in a sheet-molding compound application. In this example, 4,500 pieces of carbon fiber tape are stacked and molded into a helicopter rotor component.

To make this part, the manufacturer needed its hydraulic press to meet stringent qualification criteria, which required a 250-ton off-center load be applied 12.0" (305mm) inside the cylinder periphery. The cylinder periphery was defined as 12.0" (305mm) in from the X & Y directions of the centerlines of the cylinder rams. Deflection of no more than 0.015" (0.381mm) on a maximum 250-ton load was permitted. The guided platen could not be out of parallel to the bed by more than 0.015" (0.381mm). And the hydraulic press would be subjected to 16 hour dwells under a full load and at maximum temperature.

Press specifications to meet these criteria include a tonnage of 400, providing force adjustable from a minimum of 2,500 lb (1,134kg) to a maximum of 800,000 lb (362,873kg). The platen size is 84.0" (2,134mm) front-to-back and left-to-right and the stroke is adjustable to 14.0" (356mm). The manufacturer improved its yield by 30%.

In another example, a hydraulic press was a solution for a manufacturer working with a composite material similar to carbon fiber and infused with resin. The composite material has a short shelf life and has to be refrigerated until it is laid up in the molds. The material is cut using a template to various shapes and sizes, all having the same thickness. The cut pieces are then laid on top of each other on the template, with titanium alloy hubs in the middle. The result is a part with varying thickness due to machining and attachment requirements.

To work with this material, Greenerd custom-designed a 100-ton press delivering an adjustable force of 0.4 tons to 100 tons, settable in 0.1-ton increments. The press features an adjustable stroke of up to a maximum of 14.0", a 10hp motor capacity, and a 10.5" color Panelview electronic press control.

The part is placed in a tool that is below 100°F, to locate the end hubs. The press has a settable platen temperature for each mold half, a time setting for ramping up temperature from 100°F to the maximum required temperature, and a position setting for moving slide up to 10 sequences. The press closes to the position setting with tonnage override to just make contact with the part, and then reaches the position and platen temperature [less than 365°F (185°C) at the end of a settable time – generally 0 to 30 minutes]. This continues with decreasing positions and increasing temperatures. The temperature begins to cool by convection at a controlled rate through use of water cooling channels provided in heated platens of the press. At a settable sequence, cooling water is turned on to cure a part, set contours of tooling, and bring the tooling temperature below 100°F (38°C).
 

Complex part geometry

A manufacturer of round jet engine cowlings faced a different challenge: punching a series of holes around the circumference of a jet engine cowling. With an atypical part geometry for punching, multiple part numbers and frequent setup changes, its production process needed flexibility and streamlining.

The solution came in the form of a 60-ton press with a horn extension in place of a bed and a removable jack attachment for added support. The part is indexed around the horn during the punching operation. The operator moves it to various positions with a small tool that is mounted on the horn. Both a 9" and 6" diameter horn are used to accommodate various cowling sizes. A touch-screen with an integrated bar code scanner allows for quick changeovers between work orders. The press also features an adjustable ram force from 12 tons to 60 tons, 12.0" daylight, a 30hp motor, and a two-post guiding system.

A versatile solution

For a manufacturer drawing titanium blanks into aerospace components, a hydraulic press solution provided the flexibility necessary to efficiently form a wide variety of parts such as jet engine components. The company selected a triple action draw press with a 600-ton main ram capacity, a 300-ton capacity blankholder platen, and a 125-ton capacity cushion that delivers an adjustable punch force of 120 tons to 600 tons and an adjustable blankholder force of 60 tons to 300 tons. An Allen-Bradley Panelview 1000 Plus electronic press control provides full functionality via a touchscreen that allows a user to easily set cylinders for pressure, distance, speed, and dwell. The control is also able to store up to 100 different jobs, allowing for quick setups.

The blankholder work area measures 52.0" (1,321mm) both left-to-right and front-to-back. With a punch diameter of 12.0" (305mm), the press features a punch daylight of 48.0" (1,220mm), an adjustable punch stroke up to a maximum of 38.0" (965mm), and a punch shut height of 10.0" (254mm).

In another example, another aerospace manufacturer investigated hydraulic press technology for an effective way to handle the processes it uses to produce aerospace components, such as punching, forming and blanking. The manufacturer selected a 150-ton capacity hydraulic, four-point Gib-guided press with a 70-ton programmable cushion and a 10-ton capacity ram-mounted knockout.

Designed to handle large, off-center loads with a minimal frame deflection of .0005" per inch of throat depth (0.0127mm per millimeter), the press features a 50.0" (1,270mm) x 30.0" (762mm) table, a daylight of 36.0" (914mm) and an adjustable stroke from 1.0" to 30.0" (25mm - 762mm). The press also delivers an adjustable ram force of 30 tons to 150 tons, with a maximum of 112.5 tons for blanking.
 

An Expert Opinion

When considering hydraulic press technology, it’s important to choose a vendor who will work to understand your application and objectives and design the press that is best suited to meeting your specific requirements.

Greenerd Press and Machine Co. supplies hydraulic press solutions with product capability to 40,000 tons, bed sizes exceeding 240.0" (6,100mm), and styles ranging from gap frame and straight-side to gantry-type straightening presses.

Greenerd Press and Machine Co.
www.greenerd.com